POV-Ray : Newsgroups : povray.newusers : How can I fix surface perfections on my render? Server Time
19 Sep 2021 18:51:49 EDT (-0400)
  How can I fix surface perfections on my render? (Message 11 to 14 of 14)  
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From: Bald Eagle
Subject: Re: How can I fix surface perfections on my render?
Date: 11 May 2020 07:15:01
Message: <web.5eb932e149257b65fb0b41570@news.povray.org>
"circuit" <nomail@nomail> wrote:
> Wow, this community is awesome. I appreciate all the responses.

We try.  :)
There's always so much to do, and it's so much easier to get things _done_ when
you can get past all the hurdles.  We all help out as best we can.


> 100% sure it's a coincident surface issue. In fact, similar artifacting also
> exists in FreeCAD's rendered output. Here's an animation using FreeCAD
> "activeView":

Find min_extent and max_extent of all the parts, calculate the centers,
translate to center, scale down by a wee bit, then translate back.
With that many parts, I'd probably write a little macro that takes an object{}
as an argument.

> This is actually not my model... it's just the first demo file I found online
> that had assembly constraints, so I ran with it. I have no idea if it was
> designed properly. I plan on testing this out more thoroughly with a model I
> build myself.

Naturally.  Always a lot easier to get things moving with pre-built stuff.


> I come from an electrical
> background, but I have a strong interest in robotics. My plan is to use FreeCAD
> to design and simulate (animate) robotic gait.

Nice.   Chemist myself, but I dabble with things with my EE friend.
You should look up Rune's spider animation.  Very impressive.


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From: Alain Martel
Subject: Re: How can I fix surface perfections on my render?
Date: 12 May 2020 12:21:55
Message: <5ebacd23$1@news.povray.org>
Le 2020-05-10 à 13:09, Cousin Ricky a écrit :
> On 2020-05-10 12:18 PM (-4), Alain Martel wrote:
>> Le 2020-05-09 à 19:59, Bald Eagle a écrit :
>>>
>>>>              //default light
>>>>              light_source {
>>>>                  cam_location
>>>>                  color White
>>>>                  area_light <100, 0, 0>, <0, 0, 100>, 10, 10
>>>>                  adaptive 1
>>>>                  jitter
>>>>              }
>>>
>>> That seems - excessive?  Especially for a simple render.
>>> And it might have something to do with the weird look.
>>> Just use a standard point light source, and you'll get adequate 
>>> lighting and
>>> good shadows.
>>
>> Yes, should use adaptive 0
> 
> That depends on the scene.  I've had some scenes for which adaptive 0 
> was fine, and others for which the result was hideous.
> 

You start with adaptive 0. If it's OK, good for you. Only if there are 
some glitches do you  ever need  to use adaptive 1 or more. You rarely 
ever need to go over adaptive 2.

Just remember at what values adaptive start :
adaptive 0 start with 2x2
adaptive 1 is 3x3
adaptive 2 is 5x5
adaptive 3 is 9x9
adaptive 4 is 17x17

You need to have at least two steps more than the starting value to get 
any notable performance improvement.

Also, that 10x10 get silently upgraded to 17x17.


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From: Newt
Subject: Re: How can I fix surface perfections on my render?
Date: 19 May 2020 03:35:01
Message: <web.5ec38c0249257b65a55574d00@news.povray.org>
> I seem to have some issues with the rear spindle flashing when the wheel is
> given transparency. How can I prevent this?

For sure this is due to touching surfaces, so POV-Ray (quasi)randomly picks
which one to render. Should have some tiny amount of distance between parts, and
it will work fine...


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From: Newt
Subject: Re: How can I fix surface perfections on my render?
Date: 19 May 2020 04:45:00
Message: <web.5ec39bf949257b65a55574d00@news.povray.org>
> The issue I'm facing is that
> the output surface has a lot of imperfections around edges.

As already well put by other guys, those are radiosity artifacts, and it's pain
to clean them out... there are two parameters that must be balanced, 'count' and
'error_bound'. I will upload image in a separate post to clarify.

Generally, I combat these artifatcs by using:
-textures, image maps - not plain flat surfaces
-complex lightning scene - not single point light or sky dome
-actual environment, room, background - not object suspended in empty black
space
-focal blur - even a subtle amount works miracles
-large renders (5000+ px) - then apply small amount of gauss or other blur
filter


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